broad-banded meadow fly

Broad-banded meadow fly is a northern, medium-sized, typical hover fly. It is widespread and likely much more common than the few available records indicate. It occurs in the United States from New Hampshire to New Jersey, west to Minnesota and Illinois, and south along the Appalachian Mountains to North Carolina. It also occurs throughout Canada and in Alaska. Adults are active from late May through early October. They are found in deciduous and coniferous forests, bogs, and meadows. They feed on flower nectar. The few known records are from goldenrods, but photos on iNaturalist show them taking nectar from several species of flowers. The larvae are predators of aphids.

Adults are 5⁄16″ to ½″ (8.1 to 12.5 mm) in length. The body is hard and black with yellow markings that strongly mimic wasps.

The head is small, hemispherical, narrow, and black. The back of the head is strongly concave and closely appressed to the front of the thorax. The face is yellow with a broad, black to brown stripe in the middle. It is concave and there is a low, rounded, bump-like extension (tubercle) in the middle near the lower margin. There are two large compound eyes on the sides of the head and three small simple eyes (ocelli) in a triangle on top of the head. The compound eyes are narrowly indented on the rear margin in the shape of a broad triangle. On the male they abruptly converge and meet at the top of the head in front of the ocelli, and they are densely covered with long erect hairs. On the female they do not meet, and the hairs are shorter and slightly less dense. The antennae are long and black. When viewed from the side, the antennae are in the middle of the head and projected forward. They have three segments, all of which are elongated. The first segment (scape) is longer than the second segment (pedicel). The scape and pedicel together are shorter than the third segment (flagellum). At the base of the flagellum there is a long, forward-pointing bristle (arista) on the upper side. The arista is bare, not plume-like. The protruding mouthpart (proboscis) is short and fleshy.

The large plate on the front portion of the thorax (scutum) is black and shiny. There is a groove (transverse suture) across the scutum near the middle just before the wing bases. There is a pair of narrow, gray, longitudinal stripes on the front half near the middle, and two yellow stripes on each side near the lateral margin, one before the suture and one after the suture. The sides of the thorax are black with yellow markings. There are several plates on each side. The rear part of the plate at the upper front (anepisternum) is bright yellow. The front part of the anepisternum may be bare, or it may have one to three long, fine, pale hairs on the lower half. The plate on the underside of the second thoracic segment (katepisternum) has a bright yellow or dull yellow spot near the upper margin. It also has an upper and lower hair patch, and the patches are broadly joined together. The small plate at the rear part of the thorax (scutellum) is black and translucent with a variable amount of yellow. It may have a broad yellow border around the entire margin with a black spot in the middle, a narrow yellow border on the front or rear margin, or a narrow yellow border on both margins. On each side of the scutum, in the shoulder (humeral) area just behind the head, there is a small plate (postpronotum). The postpronotum is bare, with no hairs or bristles. Unfortunately, this is not visible without first removing the fly’s head.

The abdomen is broad, strongly convex, and black, with distinct yellow bands. The rear corners of the second through fourth abdominal segments project slightly to strongly rearward beyond the margin of the next segment. These projections (posterolateral angles) on the third and fourth segments are strongly projected forward. The upper plate (tergite) on segment 1 is entirely black. The tergites on segments 2 through 5 are black with bright yellow, slightly curved bands near the middle. The bands are broad, about one-quarter the width of the tergite. This is the feature that gives the fly its common name. The bands on tergites 3 and 4 are usually narrowly divided in the middle, rarely complete. Tergites 3 and 4 also have a narrow band on the rear margin. The rear margin of tergite 2 is usually entirely black, rarely with a very narrow yellow band. Tergite 5 has a narrow, inverted, yellow, Y-shaped mark. On the male the clasping organs (surstyli) are narrowed, tapered on the basal two-thirds, then almost parallel to the tip.

The legs are mostly yellow. On the hind legs, the third segment (femur) is usually entirely yellow, but it sometimes has a narrow black ring.

The wings are mostly clear, but they are tinted light to dark smoky brown along the leading edge (costal margin). There is a false (spurious) vein between the radius (R) and media (M) veins. The anal cell is long and is closed near the wing margin. The marginal, R₅, and M₂ cells are also closed. Cell bm is usually entirely covered with minute hairs (microtrichia). It rarely has a bare stripe in the middle.

Total length: 5⁄16″ to ½″ (8.1 to 12.5 mm)

Narrow-banded meadow fly (Chrysotoxum derivatum) is very similar in appearance. On the second and third tergites, the yellow bands are narrower, and there are extensive black hairs. The posterolateral angles on the third and fourth tergites only slightly project forward. On the hind legs, the femur is black on the basal third or more.

Deciduous and coniferous forests, bogs, and meadows

Late May through early October

Aphids

Flower nectar

Sources

24, 27, 29, 30, 82, 83.

Telford, Horace S.. (1939). The Syrphidae of Minnesota. University of Minnesota. Minnesota Agricultural Experiment Station.

Genus
Species concepts within the genus Chrysotoxum have long been debated and they remain so today. Early authors (Curan, 1924; Shannon, 1926; and others) used body (integument) color, hair color, length of hairs on the thorax, length of antennae, the presence of hairs on the rear of a thoracic plate (anepisternum), and the distribution of minute hairs (microtrichia) on the wing surface, in conjunction with other characters, to define species. However, these characters are variable within several species. The keys by those authors are now out of date. The description on this page is based on publications dated 1992, 2013, and 2019.

Species
Chrysotoxum plumeum has been treated in the past as Chrysotoxum derivatum, Chrysotoxum minor, Chrysotoxum columbianum, Chrysotoxum integre, and Chrysotoxum perplexum. It is still treated as Chrysotoxum perplexum by some sources, including BugGuide.net and Discover Life.

Alfredo Colon
6/7/2021

Location: Woodbury, MN